1. Field of the Invention
The present invention relates generally to the field of semiconductor processing, and more specifically, to supporting, positioning or rotating a substrate during semiconductor device fabrication in a processing chamber.
2. Description of the Related Art
In the fabrication of integrated circuits and displays, semiconductor, dielectric, and electrically conducting materials are formed on a substrate, such as a silicon substrate or a glass substrate. The materials can be formed by chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), ion implantation, plasma or thermal oxidation, epitaxial growth (EPI), and nitridation processes. Thereafter, the deposited materials can be etched to form features such as gates, vias, contact holes and interconnect lines. In a typical deposition or etch processes, the substrate is exposed to a plasma in a substrate processing chamber to deposit or etch material on the substrate surface. Other typical processes that may be performed on a substrate may include thermal processing techniques that may include rapid thermal processing (RTP), or laser annealing processes.
During processing, a substrate is typically held on a substrate support having a substrate receiving surface. The support can have an embedded electrode that serves as a plasma generating device during processing and/or it may also be charged to electrostatically hold the substrate. The support can also have a resistance heating element to heat the substrate during processing, and/or a water cooling system to cool the substrate or to cool the support.
One issue that arises is that as device sizes decrease the tolerance to variation across the substrate has become very low such that the alignment and positioning of a substrate relative to the substrate support, shadow ring, or other chamber components can have an affect on the uniformity of the process results achieved on the substrate.
In some cases, one or more regions in a process chamber may be unable to uniformly generate a plasma (e.g., PECVD, PVD, EPI), uniformly deliver heat to the substrate (e.g., RTP, PECVD, EPI), and/or have regions of non-uniform gas flow due to the position orientation of the gas inlet or exhaust in the processing chamber, which commonly creates the need to rotate the substrate to average out the non-uniformities seen in different areas of the processing region of the processing chamber.
Rotating the substrate is often a very expensive and complicated process to perform in a processing chamber that requires the substrate to be processed at sub-atmospheric pressures, to be processed at high temperatures and/or require one or more rotatable electrical connections to allow power to be delivered to one or more components in the substrate support (e.g., heater elements). The complexity and cost generally arises due to the need for high temperature rotational components (e.g., bearings) that are reliable and will not generate particles, precise and expensive motors, complex control systems, reliable rotating electrical connections, and reliable rotating vacuum seals.
Therefore, there is a need for an improved system adapted to support, position, and/or rotate a substrate during a substrate processing, which does not require direct contact with the substrate, is inexpensive to use and maintain, provides good process results, is reliable, and is easy to control.